Cardiovascular response elicited by mechanical stimulation of airways varies depends on the site of stimulation. The purpose of this study was to compare cardiovascular pressor responses to direct laryngoscopic nasotracheal intubation, when lidocaine was applied topically as either a nasal spray or an orolaryngeal spray before the induction of anesthesia.

Forty-six healthy adult patients were randomly allocated to two groups according to the site of the lidocaine spray before the induction of the anesthesia. Group N (nasal spray group, n = 23) received a 10% lidocaine nasal spary using a pump-metered spray (3 times into each nostril), and Group O (orolaryngeal spray group, n = 23) received the same dose and preparation in a sitting position on inspiration. After induction of anesthesia, a nasotracheal tube was inserted through a nostril. Hemodynamic data were recorded in the ward (control), after lidocaine spray, after the induction of anesthesia but before intubation, and immediately and 1min after intubation.

Nasotracheal intubation caused a significant increase in heart rate in both groups, but a significant increase in blood pressure occurred in group O only. Rises in systolic, diastolic and mean blood pressure were significantly higher in group O than that in group N immediately and 1 min after nasotracheal intubation.

Topical lidocaine administered as a nasal spray before the induction of anesthesia was found to be effective at reducing but not abolishing tachycardia response to direct laryngoscopy and nasotracheal intubation.